When environmental exposure assessment studies provide feedback to the lay public, the resultant communications generally focus on the exposure assessment itself (e.g., serum levels) and not the relationship of the exposure to health risks, perhaps due to the uncertainty of the character of this relationship. However, little is known about how persons given only exposure assessment results process such communications in the absence of health risk information, and what, if any, are the intended or un-intended behavioral responses. The National Institute of Environmental Health Science's goals include developing and using bio-markers of exposure/susceptibility of disease and focusing on populations that are exposed to high concentrations of environmental agents. An increased understanding of how people comprehend and react to exposure assessment information alone can identify issues of concern in current practice and inform effective environmental risk communication to facilitate achievement of these goals. To this end, the proposed study will capitalize on a pre-existing natural experiment: the participants and non-participants of an assessment study of dioxin exposure in the Midland/Saginaw, Michigan, area in which only exposure assessment results were provided to study participants and community members. This study seeks to: 1) examine comprehension, retention, and risk perception of messages, and change in behavior among residents who participated in a dioxin exposure assessment study and a control population who did not (both residing in the same area);2) explore the effects of health literacy, attitudinal, geographic, and personal characteristics on the comprehension, retention, risk perception, and change in behavior of these two populations;and 3) explore through qualitative in-depth interviews the mental conceptualizations of risk of a sample of participants who maximally differ on measures of comprehension, risk perceptions, and behaviors. Data collection will consist of a survey of 1,000 persons from Midland/Saginaw, Michigan, 600 of whom previously participated in the dioxin exposure assessment study and a control population of 400 who did not. Qualitative interviews will also be undertaken (n=30) with survey respondents who maximally differ in their comprehension, risk perceptions (and misperceptions), and subsequent behaviors. These interviews will enhance the understanding of the mental conceptualizations that contribute to perceptions and misperceptions about dioxin risks. The information gathered from this study will be used to improve the translation and communication of environmental risk information to the lay public. The relevance of this research to public health rests in its potential to inform better translation of scientific environmental exposure assessment information to the lay public. As NIEHS pursues its identified challenge of "developing scientific knowledge that empowers people to improve their environmental choices", we must concurrently develop better communication methods to share the knowledge gained in a way that can promote positive environmental choices among lay people. By examining how community members in a dioxin-exposed area responded to messages about exposure assessment and identifying what factors may have affected their comprehension and risk perception, this study will inform future translation of environmental exposure assessment research results into understandable communication to the lay public.